 Complicating the problem is that in many cases, teachers have the liberty to create their own lessons without much accountability. According to a 2017 RAND Corporation survey, most teachers do not strictly follow state curriculum. The American Federation of Teachers, the U.S.'s second largest teachers union, runs a Share My Lesson website. And according to an article in the Free Press, the site boasts 2.2 million members – that's about half the number of public school teachers in the U.S.,